1. Field of the Invention
The present invention relates to an evaporative fuel adsorption device, and more particularly to an evaporative fuel adsorption device that is positioned in an intake path to adsorb evaporative fuel while an internal combustion engine is stopped.
2. Background Art
A conventional evaporative fuel adsorption device disclosed, for instance, by Japanese Patent Laid-open No. 2001-227421 is positioned in an internal combustion engine's intake path to adsorb evaporative fuel (HC). In this conventional evaporative fuel adsorption device, an evaporative fuel adsorbent is directly attached to the entire inner wall surface of a surge tank in the intake path. The use of the above conventional evaporative fuel adsorption device or other evaporative fuel adsorption device having an evaporative fuel adsorbent in the intake path makes it possible to adsorb HC remaining in the intake path during an internal combustion engine stop and inhibit the HC from leaking out of the intake path.
Including the above-mentioned document, the applicant is aware of the following documents as a related art of the present invention.
[Patent Document 1]
Japanese Patent Laid-open No. 2001-227421
[Patent Document 2]
Japanese Patent Laid-open No. 2002-332924
When a blowby gas flows backward into the intake path in an internal combustion engine, oil may flow into the intake path together with the blowby gas. If the oil flows into the intake path, it adheres to the inner wall surface of the intake path. When the above-mentioned conventional evaporative fuel adsorption device in which an evaporative fuel adsorbent is directly attached to the inner wall surface of the surge tank is used in the above instance, the oil may run down on the inner wall surface and adhere to the evaporative fuel absorbent. The oil has a high boiling point. Therefore, once the oil adheres to the evaporative fuel adsorbent, the oil is not likely to leave the evaporative fuel adsorbent. As a result, when the oil adheres to the evaporative fuel adsorbent, the HC adsorption capacity of the evaporative fuel adsorbent decreases.